Answer:
Eutrophication is the enrichment of a body of water with excessive nutrients (nitrogen and phosphorus), which causes algal growth and subsequent decline of dissolved oxygen after decomposition.
Temperature is related to the kinetic energy the atoms within any given
substance. Within a solid, we can therefore assume that the density will
increase as the solid is cooled to a low temperature, as this will
cause a loss in kinetic energy and the atoms won't be able to move as
freely.
Answer:
2.1
Explanation:
Calculation of moles of 
Mass of copper = 5.3 g
Molar mass of copper = 315.46 g/mol
The formula for the calculation of moles is shown below:

Thus,

Moles of
= 0.0168 moles
According to the reaction,

1 mole of
react with 1 mole of 
0.0168 moles of
react with 0.0168 moles of 
Moles of
= 0.0168 moles
Molar mass of
= 126.07 g/mol
Thus,
<u>Mass = Moles * Molar mass = 0.0168 moles * 126.07 g/mol = 2.1 g</u>
<u>Answer - 2.1</u>
Answer: Noble gases
Explanation:
Electronegativity is the ability of an atom to gain an electron. Noble gases already have 8 electrons, so they don’t need to gain electrons. If they don’t gain electrons, it has no electronegativity.
<h2>
Answer: 8.69 × 10⁻¹ Hz
</h2>
<h3>
Explanation:
</h3>
Frequency = Speed of Light ÷ Wavelength
= (2.99 × 10⁸ m/s) ÷ (3.44 × 10⁻⁸ m)
= 8.69 × 10⁻¹ Hz
The frequency of a light of wavelength 34.4 nm is 8.69 × 10⁻¹ Hz.
<u>Notes:</u>
Hz ≡ /s
1 m = 10⁹ nm